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ETHANOL-HIF-1 ALPHA AXIS IN INFLAMMATORY GENE EXPRESSION IN
LIVER CELLS
by
Samantha Mahadevappa Yeligar
____________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOCHEMISTRY AND MOLECULAR BIOLOGY)
August 2009
Copyright 2009 Samantha Mahadevappa Yeligar

Chronic alcohol consumption leads to liver inflammation and cirrhosis. Portal hypertension and its complications contribute to mortality in patients with cirrhosis. Concomitant to inflammation and cirrhosis of the liver, alcoholic liver disease patients have increased levels of cytokines and chemokines. Ethanol-induced liver injury has also been shown to be associated with an increased presence of inflammatory cells, e.g. Kupffer cells, in the liver. Further, oxidative stress has been implicated in alcohol-induced inflammation and liver injury. However, relatively less is known about the molecular mechanisms involved in ethanol-induced inflammatory gene expression in liver sinusoidal endothelial cells (LSEC) and Kupffer cells (KC).; Our studies, in vivo and in vitro, show that ethanol increased HIF-1α mRNA and protein expressions in both liver sinusoidal endothelial cells and Kupffer cells, independent of hypoxia. Increased HIF-1α expression led to the up-regulation of (a) endothelin-1 (ET-1) and its cognate receptor ET-BR, (b) inflammatory chemokine RANTES/CCL5, (c) 5-lipoxygenase activating protein (FLAP) and (d) the phase II detoxifying enzyme, hemeoxygenase-1 (HO-1).; Moreover, ethanol-mediated activation of divergent signaling pathways in the same cell type led to up-regulation of the aforementioned genes. In LSEC, ethanol-induced ET-1 expression involved NADPH-oxidase activation, but not PI-3 kinase. However, RANTES expression augmented in response to ethanol involved activation of Protein kinase C-Src-JNK-2, but not NADPH-oxidase or PI-3 kinase. In KC, ethanol-mediated FLAP expression involved PI-3 kinase activation, but not NADPH-oxidase. However, ethanol-induced increase in HO-1 expression involved activation of NADPH-oxidase, PI-3 kinase and JNK-1. These studies suggested differential roles of NADPH-oxidase, PI-3 kinase, JNK-1 and JNK-2 in regulating the aforementioned gene expressions in response to ethanol.; Since HIF-1α mRNA and protein levels were enhanced in response to ethanol, we determined whether HIF-1α co-regulated genes could be regulated by recently identified HIF-1α-related microRNAs (miRNA). We identified miR-199 as the key miRNA involved in negative modulation of HIF-1α, ET-1 and FLAP translation. These studies, for the first time, provide a novel mechanism to fine tune the expression of these genes.; The studies described herein provide novel therapeutic approaches, based on HIF-1α modulation, to ameliorate ethanol-induced liver inflammation and injury.

ETHANOL-HIF-1 ALPHA AXIS IN INFLAMMATORY GENE EXPRESSION IN
LIVER CELLS
by
Samantha Mahadevappa Yeligar
____________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOCHEMISTRY AND MOLECULAR BIOLOGY)
August 2009
Copyright 2009 Samantha Mahadevappa Yeligar